<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>backTop返回顶部</title>
  <link rel="stylesheet" href="./backTop.css">
  <script src="./backTop.js"></script>
</head>
<body>
  
  <div style="width: 80%;height: 2000px;margin: auto;" class="content"></div>
  <div class="l-backtop">
    <span class="l-backtop-label">UP</span>
  </div>
</body>
</html>